Princetons flagship line of interlocked bristle, Refine™ starts with premium quality Chungking bristle and adds the panache of hand-formed interlock construction. The natural taper and curve of the bristle is expertly arranged within the hair tuft to form crisp edges and resilient points. Interlocked brushes hold their form in heavy use while other non-interlocked bristle can look more deranged than arranged. The true bounty of Refine™ is in its shape and size offering. Unique shapes like short filberts , extreme egberts, and sharp angle shaders usually only appear in much more expensive European ranges. Likewise, large sizes like our size 24 flat can be found across the pond for 3 to 4 times our fair price. Brush sizes – The length and width of brushes given shape and size may vary by brand as brush sizes are not standardized. Most fine art brushes are handmade and as such some variation is expected even among brushes from within a single brush line.